Forcer tube



F. W. WALCH Dec.1 26, 1939.

FORCER TUBE Filed April 26. 1938 0' THRoA-r 0mm-rre@ Patented Dec. 26,1939 UNITED STATES PATENT OFFICE FORCER TUBE Jersey Application April26, 1938, Serial No. 204,271

12 Claims.

This invention pertains to jet pumps, for example to pumps of the kindknown as injectors or inspirators commonly employed to force feed Waternto steam boilers, and relates more particularly to an improved forcertube for such a pump.

The patents to Walch No. 2,032,674, dated March 3, 1936, and No.2,046,887, dated July 7, 1936, describe highly desirable forms of forcertube. As disclosed in said patents the forcer tube comprises a receivingor combining section and a discharge or delivery section, said sectionscolle'ctively deiining a substantially straight, convergent-divergentpassage devoid of lateral out- 4vlets from one end to the other, thesections being l5` provided with oomplemental parts for securing themrigidly together at their smaller ends and with means for removablysupporting the tube in the pump casing. As pointed out in said patents`the high velocity iiuid which ows through the "forcer tube tends toerode the inner surface, particularly at any point at which the taper ofthe tube abruptly changes, and said patents describe means designed toprolong the useful life of the tube, for example, a wear-resistant linerat a cer- -tain point in the tube.

Wear-resistant material, for example, stainless steel, is quite dicultto machine, and the possibility, as a practical matter, of making theentire tube of such a wear-resistant substance has been T"seriouslyquestioned in view of the difficulty involved in providing for the unionof the tube sections and in providing a suitable mounting whereby thetube may be positioned within the pump casing. Previous methods ofuniting the tube sections have also substantially precluded the use of athin-walled tube, although, when using such an expensive material asstainless steel, a decrease in Wall thickness would be desirable inorder to reduce the cost of manufacture.

' The present invention has for one of its objects the provision oi animproved forcer tube (useful in either the axial flow or the non-axialflow type of injector) having provision for uniting its two sections andfor supporting the tube as a Whole,

*such that a minimum of machine work is required Cl. 10S- 277) sagechanges abruptly. It has commonly been the practice to bore the tubesection with a series of straight tapers for convenience in machining,but where two such tapers converge, rapid wearv takes place. A furtherobject of the present in- 5 vention is to provide a forcer tube havingan inner surface of such contour, to'wit, a substantially continuousstreamline taper as to eliminate those flow conditions which appear tobe responsible for localized wear, and thus greatly to prolong the lifeof the tube, whether or not it is made in whole or in part ofwear-resistant material.

Other objects and advantages of the invention will be pointed out in thefollowing more detailed description and by reference to the accompanyingdrawing wherein Fig. 1 is a longitudinal diametrical section showing aforcer tube constructed in accordance with one desirable embodiment ofthe present invention;

Fig. le is a fragmentary section illustrating the mounting of the tubein an injector casing;

Fig. 2 is a longitudinal section illustrating a modified construction;25"

Fig. 3 is a fragmentary section similar to Fig. 1, l but showing afurther modification;

Fig. 4: is a longitudinal diametrical section, showing a constructiongenerally similar to that of Fig. 3, but in which the walls of the tubesections are of thin material, for example, sheet metal;

Fig. 5 is a transverse section substantially on the line 5-5 of Fig. 4;and

Fig. 6 is a diagram illustrating, merely by Way of example, onedesirable curvature for the bore of the tube such as to avoid theformation of eddies or other breaks in the continuity of the flowingstream which are apparently responsible for rapid localized wear. 40

Referring to the drawings and particularly to Figs. 1 and 1a, theimproved forcer tube l is shown as comprising the vcombining portion 2and a delivery portion 3 which are arranged in endto-end axial alignmentthereby to provide a substantially straight passage devoid of lateraloutlets from one end to the other. I'he combining tube 2 has a largereceiving end 4 and a small end 5, While the delivery tube section has alarge discharge end 6 and a small receiving end 1. The small ends 5 and'l of the respective tube sections are provided with telescoping parts5a and 'la respectively, whose meeting surfaces are preferably iinishedsmoothly, as for example by grinding so that the smaller ends of thetubes snuglyinter- 55 fit and so thatno appreciable crack or creviceoccurs at the joint between them.

For holding the tube sections 2 and 3 in proper relative position andfor supporting the tube as a whole in the injector casing, there isprovided a sleeve device 8, shown in Fig. 1 as comprising asubstantially cylindrical portion 9 which embraces thesmaller ends ofthe tube sections and which is provided at its right-hand end as shownin Fig. 1 with an inwardly directed flange I0 having a substantiallyradial abutment face which normally engages a complementary radialabutment face on a peripheral shoulder I I of the tube section 3.

The sleeve device 8 also comprises the cylindrical portion I2 which isinternally screw threaded for engagement with exterior screw threadsformed on an integral part I3 of the tube section 2. The member I2 ofthe sleeve device is also externally screw-threaded at I4, suchscrewthreaded portion terminating `at a shoulder having a substantiallyradial abutment surface I5. Preferably the sleeve device is alsofurnished with wrench-receiving parts W for engagement by an 25.appropriate wrench device whereby the tube as a whole may be mounted inor removed from the injector casing.

As illustrated in Fig. la, the injector casing I6, which may consist ofseveral parts secured together, for example by bolts B, comprises theinlet chamber Il and the outlet chamber I8 separated by an annulardiaphragm member or abutment shoulder I9 which is internallyscrewthreaded for the reception of the screw-threaded .portion I2 of thetube-supporting sleeve device. 'This diaphragm is provided with a radialstop surface 20 against which the radial face I5 of the sleeve deviceabuts when the sleeve device is in operative position in the casing.When thus mounted in the casing, the combining tube section 2 'isdisposed within the chamber l'l and the delivery tube section 3 isdisposed within the chamber I8 of the casing. As more fully described inthe patent to Walch above referred to, the casing is furnished with aremovable check valve housing (not here shown) at the end of the chamberI 8, and by removing this check valve housing the improved tube with itsparts assembled may be introduced as a whole into the casing or removedtherefrom.

The external diameter of the tube section 3 is preferably substantiallyuniform from its end 6l to the radial abutment face II, and the sleevedevice' B may be slipped on to the tube section 3 at the right-hand endof the latter and moved to the left, as viewed in Fig; l, until itsfiange I abuts the part II. The smaller end of the tube section 2 maynow be introduced into the sleeve device and by relative rotation of thesection 2 and the sleeve device, the tube section 2 may be screwed intothe sleeve device until its smaller end rmly abuts the smaller end ofthe tube section 3. For convenience in such relative rotation of thetube section 2 and the sleeve device, tube section 2 may be providedwith wrenchreceiving elements w.

It may be noted that very little machine work is required to be done onthe tube sections 2 and 3. These sections may, for example, be diecastings or drop forgings and the necessary machine work for finishingthem requires little more than the proper grinding of the abutment faceon shoulder II; the grinding of the abutting surfaces of the smallerends of the tube sections; and the formation ofthe' screw threads uponthe part I3. It is thus possible to make both tube sections, if desired,of some hard, wearresistant material diliicult to machine, such forexample as stainless steel, while on the other hand the sleeve device,which is or irregular contour including the wrench-receiving members W,may be made of some relatively soft and easily workable material, as forexample cast iron, brass, or bronze.

It may further be noted that with this arrangement the entire tubestructure may be removed as a unit from the injector casing and thateither tube section 2 or 3 may be renewed without renewing the other, inaccordance with the amount of wear shown by the respective sections.

In Fig. 2, alslightmodication is illustrated wherein the tube sections2a and 3a have the interengaging, telescoping portions e and 'ila attheir smaller abutting ends, as in the arrangement previously described.In this instance the sleeve device I3a is somewhat longer than thesleeve device 8 of Fig l, and the part 9a of this sleeve device overlapsthe tube section 3f to a greater extent, thus assuring a very rigidconstruction. The part 9a of the sleeve device is furnished with theradial inwardly projecting flange portion Illa having an abutment facefor contact with the complementary abutment shoulder II a of the tubesection 3u. The tube section 2iL is furnished with the externallyscrew-threaded portion I 3a for engagement with the internal screwthread provided in the sleeve device but in this arrangement theexternally screw-threaded portion |22L of the sleeve device is spacedaxially from the screw threads Ii. The sleeve device has a shoulder orabutment face E53 and when the sleeve device is screwed into theinjector casing this abutment face 45a constitutes a limiting stop todetermine the operative position of the forcer tube.

In Fig. 3, a further modification is illustrated wherein the tubesections 2b and 3b have their smaller ends in abutting relation butl donot telescope one over the other. The smaller end portions of the tubesections are furnished with peripheral groovesZI and 22 respectively,and these grooves receive split flange rings 23'and 2li, respectively.The connecting sleeve. device comprises the parts 25 and 25 which are sounited that they may be moved axially with respect to each other, thuschanging the eiTective length of the sleeve device, as for example byhaving interengaging screw-threaded portions, as shown at 2l. The member26 of the sleeve device is furnished with a substantially radial face atthe inner side of its end flange 28 which engages the radial surface ofthe annulus 21E-while the sleeve member 25 is furnished with a radialface 29 which engages the radial face of the annulus 23. The member 25of the sleeve device is also provided'with external screw threads atwith an abutment face Ib for mounting it in the injector casing.

In assembling the parts of the device of Fig. 3, the members 25y and26`being separated are first slid onto the smaller ends of the tubesections 2b and 3b, respectively, and then the split rings 23 and 24 aredisposed in the grooves 2l and 23 thereby providing abutment shoulders,The sleeve members 25 and 26 are then brought into engagement and by.relative rotation are drawn toward each other thereby forcing the rings23 and 24 toward each other and so clamping the tube section 2b and 3hvery. lirmly together in axial alignment.` Preferably the parts 25 and26 I2b andY In Figs. 4 and 5 a further modification is illustrated. Inthese gures the tube sections 2c and 3c are of relatively thin material.For example, these tube sections may be made of drawn seamless tubingor, alternatively, of sheet material formed up into a tube and weldedalong the longitudinal joint. Since these tube sections are of thinmaterial their exteriors taper substantially in the same way as theirinteriors. Such taper of these tube sections may for example be producedby the metal working operation known as spinning or by pressure withinsuitable dies or the like. If formed from drawn steel tubing theinternal grain structure of these tube sections will be characteristicof drawn tubing with the fiber running longitudinally.

However these tube sections may be formed, they are preferably providedat their smaller ends with integral out-turned anges 32 and 33,respectively, whose abutting radial faces may be faced off true andsmooth, for example by grinding, so that there will be no appreciablecrevice where the tubes join.

In order that the tube structure may be stiff enough and properlysupported in the casing, it is contemplated that the smaller ends of thetube sections may be embraced by substantially rigid sleeve members 3dand 35, respectively, which may be as long as desired, in fact, they mayextend tc the ends of members 2c and 3C so thatV the latter in effectbecome linings. Preferably the adjacent ends of these sleeve members arefurnished with radial anges 36 and 37, respectively, between Which theabutting flanges 32 and 33 of the tube sections are interposed.Preferably split annuli 38 and 39 are arranged to embrace the reinforcemembers 34 and 35 adjacent to the flanges 36 and 31, and these splitannuli 38 and 39 are forced toward each other in assembling the tubeparts by the action of asleeve device similar to that of Fig. 3comprising the relatively movable members 25 and 26, which havescrew-threaded engagement with each other. The parts 38 and 39constitute rigid forcer members for transmitting pressure from the parts25 and 25 to the flanges 36 and 37, thereby to clamp the flanges 32 and33 firmly together.

The reinforce sleeves 34 and 35 are split so as to facilitate theirmounting upon the tube sections 2c and 3c after the latter have beenanged, but under some conditions it is contemplated that the reinforcemembers 34 and 35 might each be an integral tubular element which wouldbe slipped over the end of its corresponding tube section before thelatter was flanged.

In assembling the tube sections 2c and 3, the flanges 32 and 33 areplaced in contact, the separated members 25 and 26 are slipped over theiianged ends of the sections, the split reinforce members 34 and 35 arethen put in place, the split annulae 38 and 39 are disposed over thereinforce members 34 and 35, and the sleeve members 25 and 2S are thenscrewed together, thus holding the parts rigidly in assembled relationand in readiness for mounting in the injector casing, it being notedthat the member 25 is furnished with external screw threads at I2b andwith a shoulder at 15b, as described with reference to the structure ofFig. 3. It is contemplated that either or both of the tube sections 2and 3c may be made of some hard, wear-resistant material, for examplestainless' steel or the like, while on the other hand the various partsincluding the reinforcing members 34 and 35 of the sleeve device may bemade of some other softer and easily workable material such as brass orcast iron.

In the several figures of the drawing, the tube ystructure isillustrated as having a convergent,

divergent bore, the convergent, divergent portions in longitudinalsection being shown as smoothly curved from end to end, as distinguishedfrom the series of tapers universally used heretofore as anapproximation to such curvature. These smooth curves may be produced inAany desired manner, as for example by a boring, reaming, or grindingoperation or, in the case of the tube structure of Fig. 4, the desiredcurve may be produced as above suggested by spinning, or by pressurewithin a suitable die.

Merely as illustrative of the characteristics of a desired curvature butwithout any intent to limit the scope of the invention thereby, anapproximation to a theoretically proper curvature is diagrammaticallyillustrated in Fig. 6. In this view C represents a portion of the innersurface of the combining tube section, and C' the inner surface of thedelivery tube'section. These surfaces merge at their smaller ends toform the throat which, by reason of the atness of the curvature at thispoint, is approximately cylindrical. The length of this cylindricalthroat portion preferably approximates 1,410 the total length of thebore of the tube.

The proper curvature may be defined, for example, as follows, assumingthat the throat diamf eter is D inches. Taking the radius R as theradius of curvature of the combining section, then R=42-84D where thecenter of curvature is in a plane perpendicular to the axis of the tubeat the junction of the combining tube with the throat, while the radiusof curvature of the delivery tube is represented by the formulaR=87.7D,the center of curvature being in a plane perpendicular to theaxis of the tube and through the junction ofthe throat with the deliverytube.

As a specific example of a proper curvature arrived at in another way,and assuming a throat diameter of 0.598 and a throat length of 1k, then,if intervals of 1A" be laid off along the axis of the tube, the internaldiameter, of the tube at such successive intervals will approximate thevalues indicated by the series S for the combining tube and by theseries S for the delivery tube, at least at the central part of the borewhere exactitude of curvature is of great importance.

Such a curvature provides smooth, substantially unbroken flow devoid ofeddies which for convenience maybe termed streamline ow. As above noted,such a curve avoids localization of wear and a tube thus curved has auseful life far in excess of any tube heretofore made in which the boreconsists of a plurality of distinct substantially straight tapers whenfollowing the other.

While certain desirable embodiments of the invention have beenillustrated and described by way of example, it is to be understood thatthe invention is not necessarily limited to these precise embodiments,but is to be regarded as particularly inclusive of all equivalentconstruction, such as fall within the terms of the appended claims.

I claim:

1. A forcer tube for use in an injector casing kindependent of thecombining section,

shoulder for centering and positioning the tube, the shoulder having asubstantially radial stop surface, said tube comprising a, convergentcombining section and a divergent delivery section the smaller ends ofsaid sections having accurately nished abutting surfaces, the sectionscollectively forming a continuous passage `devoid. of lat-- era-loutlets, and a tube-supporting sleeve device independent of butembracing the tube sections at their smaller end portions and bridgingthe joint between them, the sleeve device having an external shoulderconstructed and arranged to engage the annular abutment shoulder of thecasing, said external shoulder of the sleeve device having an abutmentsurface which is complemental to thestop surface of said internalshoulder with which it engages.

2. A forcer tube for use in an injector casing of the kind which has anannular abutment shoulder loi' positioning the tube axially, said tubecomprising a convergent combining section and a divergent deliverylsection, said sections being coaxially arranged and collectivelyproviding a passage devoid of lateral outlets, a supporting sleevedevice independent oi' but concentric with at least oneof said sections,the sleeve device having an external peripheral shoulder constructed andarranged to engage the abutment shoulder' of the casing, said externalshoulder of the sleeve device having an abutment surface which iscomplementa] to the surface of the internal shoulder of the casing withwhich it engages, the sleeve device also having an element constructedand arranged to engage a coperating part of the casing thereby to retainthe sleeve and tube in place, the sleeve device also comprising partsoperative to apply clamping force to the respective tube sectionsthereby forcibly to draw them toward each other.

3, A forcer tube for use in an injector casing of the kind which has anannular abutment shoulder for positioning the tube axially, said tubecomprising a combining section and a delivery section independent of thecombining section but arranged coaxially with the latter, atube-supporting sleeve device concentric with the smaller ends of thetube sections and bridging the joint between them, said sleeve deviceincluding. an inwardly directed element and one of the tube sectionshaving-a substantially radial surface with which said element of thesleeve device engages, and means reacting between the sleeve device andthe other tube section to draw the tube sections axially toward oneanother', the sleeve device having an external shoulder provided with asubstantially radial face constructed and arranged to engage acomplemental stopY surface of the positioning shoulder ol' the casing,the sleeve also having an external screwthreaded portion constructed andarranged to engage an internally screw-threaded portion ci the casing,and wrench-receiving elements upon the exteriorof the sleeve device.

4. A. forcer tube for use in` an injector casing of the kind which hasan internal annular irl-- ternally screw-threaded abutment shoulderhaving a stop surface for positioning thetube axially, said tubecomprising convergent and divergent tube sections having their smallerends telescoped one within the other and having accurately iinishedengaging surfaces thereby collectively to provide a passage devoid ofcrevices or lateral outlets, and a sleeve device independent of the tubesections and embracing the small ends of the tube sections and havingparts cooperative with the tube sections to draw the latter forciblytoward one another, the sleeve device having external screw threadsadjacent to that end which overlaps the combining tube section andengageable with the internal screw threads of the abutment shoulder, thesleeve device also having an abutment surface at the forward end of saidexternal screw threads operative to engage the stop surface of theabutment shoulder of the casing, the sleeve device also having externalwrench-receiving elements.

5. A forcer tube for use in an injector casing of. the kind which has anannular internally screw-threaded abutment shoulder for centering andpositioning the tube, said tube comprising combining and deliverysections coaxially arrangedy a tube-supporting sleeve device embracingthe tube sections Yat their smaller ends and bridging the joint betweenthem, said sleeve deviceincluding an inwardly directed gripper element,one-.of the tube sections having a substantially radial face forengagement by said gripper element, said sleeve device having aninternally screw-threaded-portion and the other tube section having acomplemental externally screwthreaded portion engageable therewithwhereby rotation of the sleeve device draws the two sections toward eachother, the sleeve device hav-- ing external screw threads adjacent toone of its ends for engagement with the internal screw threads of theabutment shoulder of the casing, the sleeve also having an abruptabutment surface at the inner end ofY said external screw threadsoperative to engage the stop surface of the annular abutment shoulder ofthe casing, the sleeve device also having external wrench-receivingelements.

6, A forcer t-ube having a bore comprising a convergent combiningportion and a divergent delivery portion and having a-substantiallycylindrical portion approximately midway its Iength, said cylindricalportion being approximately one-iortieth of the length of the tube, theinner surface of the convergent and divergent portions respectively ofthe tube each being smoothlycurved in longitudinal section substantiallyfrom end-tovend, the curvature of the divergent portion being of greaterradius than that of the convergent portion.

7. A forcer tube having a bore comprising a convergent combiningportion, a divergent delivery portion, and a throat connecting thesmallerends. of the combining and delivery portions, the longitudinalcurvature of the inner wall of the combining and delivery portions,respectively approximating circular arcs struck on centers located inplanesperpendicular to the axis of the tube at the smaller ends or thecombining and delivery sections, respectively, the radius R. ofcurvatureof the combining tube being represented bythe formula R=42.84Dwhere D is the diameter of the throat, and the radius of curvature ofthe delivery tube section being represented by the formula R=87.7D.

8. A forcer tube havinga bore comprising a convergent combining portionand a divergent delivery portion, the inner surface oi each of saidportions in longitudinal section being a smoothly continuous curvesubstantially from end to end, the radius of curvature of the deliverysection being of the order of twice as great as that of the combiningsection.

9. A forcer tube for use in an injector casing of the kind'- which hasan annular abutment tween them, said sleeve device having an exterf nalshoulder constructed and arranged to engage the annular abutmentshoulder of the casing and comprising two relatively movable partshaving screw-threaded engagement with one another whereby relativerotation of said parts varies the eiective length of the sleeve device,each of said parts of the sleeve device having a substantially radialinterior face, and each of the tube sections having a flange abuttingthe respective radial interior faces of the sleeve device.

10. A forcer tube for use in an injector casing of the kind which has anannular abutment shoulder for positioning the tube axially, said forcer-tube comprising a combining section and a delivery section` coaxiallyarranged and disposed with their smaller ends in abutting relation, atube-supporting sleeve device embracing the tube sections at theirsmaller ends and bridging the joint between them, said sleeve devicehaving an external shoulder constructed and arranged to engage theannular abutment shoulder of the casing and comprising two relativelymovable parts having screw-threaded engagement with one another wherebyrelative rotation of said parts' varies the effective length of thesleeve device, each of said parts of the sleeve device having asubstantially radial interior face, and each of the two tube sectionshaving a peripheral groove and a radially projecting iiange memberseated in such groove, said ange members abutting the respective radialinterior faces of the sleeve device.

11. A forcer tube for use in an injector casing of the kind which has anannular abutment shoulder for positioning the tube axially,` said tubecomprising a combining section and a delivery section, each of saidsections having an integral radial ange at its smaller end, andtubesupporting means comprising parts operative to draw the end faces ofsaid flanges forcibly into contact, said supporting means including anexternal shoulder constructed and arranged to engage the annularabutment shoulder of the casing for positioning the tube axially in thelatter and an element cooperable with a corresponding element of theinjector casing thereby to' support the tube in operative position.

l2. A forcer tube for use in an injector casing of the kind which has anannular abutment shoulder for positioning the tube axially, said tubecomprising a combining section and a delivery section, each of saidsections being of seamless sheet metal of substantially uniformthickness throughout and having their smaller ends juxtaposed .and tubesupporting means comprising a sleeve device coaxial with said tubesections at their smaller ends and including an external shoulderconstructed and arranged to engage the annular abutment shoulder of thecasing for positioning the tube axially of the casing and an elementcooperable with a corresponding element of the injector casing thereb-yto secure the tube in operative position.

FREDERICK W. WALCI-I.

